title: Study of complexes of a tryptophan-free mutant of E. coli trp aporepressor with tryptophan analogues using optically detected magnetic resonance (ODMR).
abstract: Phosphorescence and optically detected magnetic resonance (ODMR) spectra of tryptophan (W) and several of its analogues (4-, 5-, 6-methyltryptophan (MeW); 4-, 5-, 6-fluorotryptophan (FW); 5-bromotryptophan) are compared with those of complexes formed with the W-free trp aporepressor from Escherichia coli (W19,99F). W19,99F binds W and each analogue except 4-FW with an estimated KD < or = 30 microM; triplet state spectroscopic and kinetic effects that accompany binding at the corepressor site are reported. ODMR data for the MeW isomers are presented for the first time. No binding of 7-azaW is observed, in agreement with the low affinity found by previous workers.
authors.affiliation: Department of Chemistry, University of California, Davis 95616, USA.
authors.forename: A
authors.initials: A
authors.lastname: Ozarowski
authors.forename: J Q
authors.initials: JQ
authors.lastname: Wu
authors.forename: A H
authors.initials: AH
authors.lastname: Maki
mesh_terms: D001059:Apoproteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins; D004926:Escherichia coli / Q000737:chemistry*; D007700:Kinetics; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism*; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins
chemical_list: D001059:Apoproteins; D001426:Bacterial Proteins; D012097:Repressor Proteins; D014364:Tryptophan; C027190:TRPR protein, E coli; D029968:Escherichia coli Proteins